Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<cstdio>
#include<algorithm>
#include<iostream>
using namespace std;
char s[100][100];
int n,m,tot;
int qx[10000],qy[10000],h,t,dep[100][100];
int dx[4]={0,0,1,-1};
int dy[4]={1,-1,0,0};
int main()
{
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++)
	{
		scanf("%s",s[i]+1);
		for (int j=1;j<=m;j++) if (s[i][j]=='.') tot++;
	}
	qx[++t]=1,qy[t]=1;dep[1][1]=1;
	while (h<t)
	{
		int nx=qx[++h],ny=qy[h];
		//cout<<
		for (int k=0;k<4;k++)
		{
			int xx=nx+dx[k],yy=ny+dy[k];
			if (xx==n&&yy==m) {printf("%d",tot-dep[nx][ny]-1);return 0;}
			if (xx>=1&&xx<=n&&yy>=1&&yy<=m)
			{
				if (!dep[xx][yy]&&s[xx][yy]=='.')
					dep[xx][yy]=dep[nx][ny]+1,qx[++t]=xx,qy[t]=yy;
			}
		}
	}
	printf("-1");
}